Burglar and fire alarm



Mmh 24, 1925.,k l lpssfss G. SCHMDT BURGLAR AND FIRE ALARM Filed March 4, 192C) Patented Mar. 24, 1925.

UNITED' STATES i GEORG SCHMIDT, F

BRRLIN-REINICKENDORF, GERMANY, AssIGNoR To ALBERT AMRHRIN, or GENE, SWITZERLAND.

BURGLAR AND ALARM.

Application led March 4:, 1920. Serial No. 363,348;

To all 'whom t may concern:

Be it known that I, GEORG SCHMIDT, residing at No. 5 Hollanderstrasse, Berlin- Reinickendorf, Germany, have certain new and useful Improvements in Burglar and Fire Alarms, of which the following is a specification.

The. invention relates to a burglar and fire alarm system in which a burglar or fire detecting device or devices are placed in the room or rooms to be protected and a signal or signals are transmitted by these devices to a supervising orattendant station. In `this invention the known principle isy used of causing a detector which is sensitive to light (such as a selenium cell which changes its electrical resistance when vexposed to light) to give rise to the actuation ofan` electric relay, which in turn closes an electric alarm circuit.

The invention consists in a form of casing in which a selenium cell is enclosed, in an rl-wm nwnhanism. and a kind of switch that enables all of the required circuit combinations to be established. This switch may be moved from its initial or zero position into four other positions in each of which its contact arms prepare or close the necessary circuits.V In the first position a supervisory lamp isswitched on, this lamp then indicating that the shutter of the selenium detector casing, is properly closed. In the second position a connection is established between the selenium cell and the relay which is caused to be actuated by it, and for purposes of adjustment a circuit is temporarily. closed by hand during the existence of which an adjustable contact of the relay may be set so that its movable pointer,

or circuit closer is swung into touch with the adjustable contact in response to a certaip change of condition of the `selenium cel In the third position of the switch the shutter of the casing in which the selenium cell is enclosed is o ened and the cell exposed, and this position of the shutter is verified by the previously mentioned supervisory lamp.

And finally. in the fourth position of the multi-way switch an electrom'ag'netically actuated switch and the selenium cell are connected to the relay and the batteries so that, if the selenium cell is now exposed to light, or if the circuit of the selenium cell invented is opened, the said movable pointer will come into touch with its corresponding adjustable contact and this ,will cause the p alarm circuit to be closed by the said electroniagnetically controlled switch.

When the multi-way switch is turned back into its initial position the alarm bell, lamp, electromagnetically controlled switch and selenium cell are switched oi in the opposite order and ythe lightv is again shut' out from the cell. 'f

The invention is diagrammatically illustrated in the drawing.

In the detector casing V, which is placed in the roo-m that is to be protected, a selenium cell J is enclosed, this cell being generally guarded against exposure to light by a pivoted shutter g which is arranged to be mechanically locked in its closed position. The casingl also contains a pair of magnet coils o which, with the aid of the armature a, serve to return the shutter g to its closed position. The rotary armature is pivoted between the pole faces of the electro magnet 0 and as it is Z-shaped it can 'be turned by the magnetic field through an angle of 90.

Mounted upon the shaft of the armature is a. detent wheel g, which engages with a detent attached to an armature t and locks the shutter in its closed position. A coiled spring h Vattached to the armature z tends to turn this armature .aand the shutter coupled therewith, so as to expose the seleniurn cell but is prevented from doing so by a detent attached to the armature t of the electromagnet 'l'. When the rotary armature a and shutter g are in the position shown in the drawing the sl ring h is tensioned so that the. lifting o the armature detent t from the detent wheel g results in a rotarv movement being imparted to the armature a. and the shutter Also mounted upon the shait of the rotary armature is a, contact arm fv, which overns the circuits through which current 1s supplied to the coils of the detecting device and to the supervisory lamp The .arrangement of the sets of contact sprlngs z and 'n is such as to enable an number of detector boxes with different windlngs'tto be electrically controlled from the supervisors device or alarm station. The. means provided for the pu ose comprlsesw the two terminals XV and VI, from which wires are run, in well-known manner to another which, on the conclusionfof the operation of terminal XIII of the first device.

f paratively fee le the next detector box', this latter may cut the succeeding box in and out of circuit in` a slmilar manner. The circuit from terminal XI of the first device V by wire-10, electromagnet p, contacts 2 i to terminal XIII is interru ted'at 2 i; and a new circuit is formed rom the terminal XI of the second device, which has identical parts with the first, through wire 10, electromagnet p, contacts '2 i to terminal XIII of the second device, thence to terminal XVI` of the first device, contacts 1 i, and thus back tothe Also a circuit which formerly ran from terminal XI of the first device by wire 10, electromagnet g, contacts nl n, wire 2, and terminal 'XII is interrupted at nl n; and a new circuit established from terminal XI of the second device V1 through its wire 10, electromagnet g, contacts n1 n, wire 2, to its'terminal XII, thence to terminal XV ofthe first device, contacts n.2 ln., wire 2, to its terminal XII. The selenium cell circuits of all devices are in parallel, for obvious reasons.

B1 is a central batter which supplies current for energizing t e magnet coils that open and close the shutter ,the electromagnetic switch lC, the'bell (g, the lamp L, the electric sup ly-main switch E, the electric `door lock 'R and the tell-tale lamp D. B2 is a closed-circuit battery for energizing a moving coil relay Rand the selenium cel J. An`open-c'ircu-it-contactl H and a distant control thermometer F- may also be connected to the closed circuit battery B2.

The supervisors or attendants devlce K contains an alarm bell G and a lamp L which serves as a signal for indicating the position of the shutter on the distant detector box. The device if( also comprises an electromagnetic switch C which, by means of its switching arm m and the contact springs e1, e2 establishes direct connections between the battery/B1 and the bell G and lampV L and also effects other ci-rcuit combinations. `The switch C also establishes direct connections between the battery B1 and the door lockV T and supply-main switch E. It is arran ed to be actuated b comcurrents whici are switched on and ofi" by the moving coil rela R. lThe electromagnetic switch C thus re ieves the sensitive contacts of the moving coil relay of the necessity of switching on co-operates with k1, k2.

and off the comparatively strong currents required for the lamp L, the bell G, etc. The function assigned to the door lock Tis to lock the doorl of the room containing the detector box the moment an alarm proceeds from this room and the electric supplymain switch E is provided for the purpose of simultaneously switching on the electric light, for which reason it is connected as indicated to the electric supply main N. The electric door lock T can be unlocked from any desired point by means of a push button contact p.

The circuits extending between the selenium cell J and the supervisors device K are controlled by a two-arm switch A which may be brought into five positions, in four of which circuit combinations are established. 'Ihe one arm of the switch A controls thecircuits for actuating the shutter g and the electromagnetic switch C, which circuits include the contacts of the moving coil relay R, and the other arm establishes circuits including the selenium cell J and the windings of the moving coil relay R.

-The switch A comprises a base and contact strips a, b springs f1, f2, f3, f", f, and

a pivoted spring switching member Sch' mounted thereon. The switching member carries two insulated contact 'closers' c1, c? which are adapted to establish electrical connections between the contact strips a, b and the sprin fly/2, f3, fand f5. The springs f1, f2, are connected by the contact closer c1 to the central battery B1, and the springs f* and f are connected by the vcontact closer c2 to the closed circuit battery B. Connected to the closed circuit battery B is the moving coil relay R, which is. of a knownI type and whose movable contact z As long as the installation is switchedoff no current flows in any of 'the circuits and the switching member Sola. of the switch A is in the position shewn in the drawing.

To prepare the installation for operation the switch A is turned in a clockwise direction so that the contact closer c1 makes' contact with the spring f1. A circuit is then closed. which may be traced as follows:

two adjustable contacts From the positive pole of the central battery B1. through the wire l lto the terminal IX, thence "through the next wire 1, the contact strip aand the contact closer c1 to the spring f1. At the spring f1 the current divides, vone part flowing through the wire 2, terminal V, next wirel 2 to the spring n and thence .partly through the s ring fn through the wire 2 to the terminal -V, and partly through the contact arm v, wire 4, terminal XIV, next wire 4, terminal VI, wire 4, lamp l, and thence through the wire 3 and terminal w to the next wire 3 backv to the negative pole of the battery B1.

other partof the current that divides at A spring f1 flows from this spring through v feeble or strong light.

the Wire 5, coil y, wire 3, back to the negative pole ot the Vbattery B1. j

It is thus seen that in this position of the switch A the lamp L is closed if the shutter g closes the detector box so as prevent the penetration of light to the solenium cell. This is importantbccause the detector box V with the Selenium cell J and the supervisory or alarln device are installed in different places or rooms and the signal lamp at the supervisory station affords a means of checking the position of the distant shutter g. The -coil y off the electromagnetic switch C is also energized so that the armature that is fixed to the contact arm m is attracted and pulled away from the springs e1, e2 which are insulated from each other.

The second position of the switch A is the adjusting position. and it is when the switch is turned into this position that the device is adjusted so as to be capable of responding to the changes effected in the selenium cells when these are exposed to a The switch A is brought into its second position by shifting its contact closer c2 into contact with the spring f4. In addition to this a temporary electrical connect-ion is made with the aid of a strip of metal p between the contact strip a and the. spring f3. In the accompanying drawings this strip is shown as pivoted to the stationary spring f3, and

adapted to be swung into and out of a position between f8 and a.

A current will now flow from the positive pole of the battery B2 through the wire 8 to the terminal I, and thence through the next wire 8 through the terminal XVII, selenium cell J, terminal XVIII, wire 9, to terminal III and through the winding fw of the relay R', -thence through 'wire 19, spring ft, contact closer c2, contact strip b wire 29, terminal II back to the negative pole of the battery B21 By the current flowing in this circuit the movable contact Z of the relay R will be deflected to a certain degree corresponding to the current that is allowed to flow by the resistance of the unexposed selenium cell. Besides the current in the selenium cell' circuit another circuit is established which may be traced from the positive pole of thecentral battery B1 through the wire 1, terminaLIX, next wire 1, contact strip a, temporary connecting strip p. spring f3, Wire 16, safety fuse S, next wire 16, and thence-to the contacts k1, k2 of the relay R. If the adjustable contact k2 of the relay R is now brought into contact with the movable contact Z, the current path will be continued from k1 orf:2 to the contact Z and thence through the next wire 26, magnet coil ofthe electromagnetic switch C, wire 3, terminal X, next wire 3 and back to the negative pole of the battery B1. By the circuit thus established through the moving coil relay the armature to which the contact arm m is fixed is attracted by the `coil of the electromagnetic switch, and

- the arm m vbrought into contact with the springs e1, e2 so that current will now flow directly from the battery through the wires 12, 13 and 14 to' the) alarm signals. `This current ma)v be traced from the positive pole of the battery B1 through the wire 1 to the terminal IX and thence through the next wire l through the contact strip a, spring f3. wire 6. contact arm m, to the springs el. e2. Here the current divides, one -part flowing through the wire 12 tothe bell G. a second part through the wire 13 to the lamp L, a third part through the wirel 14 to the terminal VII and by wire 34 through the door lock T and by wire- 24 the supply-main switch E. and these branch currents return through the wires 3, 23', 33 and terminal X back to the negative pole of the battery B1. To effect the proper adjustment of the moving coil relay so as to make it properly responsive to the changes of resistance of the selenium cell, the adjustable contact k2 is shifted a slight distance away from the movable contact Z, andthe contactarm m is moved away by hand lfrom the springs e1, e2 so as to deprive the bell G and lamp L of current. When the system has been nicely adjusted by these manipulations the temporary metallic connection p between the spring f3 and the contact strip a is removed.

When the switch A is moved into the third position, in which the contact closer c1 establishes connection with the spring f2, a current flows from the positive pole of the battery B1 through the wire 1. terminal IX, next wire 1 to the contact strip a, and thence 1 through the contact closerl c1 through spring f2. wire 7, terminal IV, wire 7 terminal XIII. spring ring 2, magnet coil r, wire 10, terminal next-Wire 10, terminal X and back to the negative pole of the battery B1. This current energizes the magnet coil r causing it to attract the armature t and release the detent wheel (l and thus allowing the tension'ed spring h to turn the armature 2, and the shutter g' through an angle of so as to'expose the selenium cell to light from without thedetector box. The turning of the armature also results in the contact arm/v being moved into contact with the spring 'i and in this spring being separated from 2 and pressed against il. By thesepa'ration of the springs and i2 the coil r is cut out of circuit and by thec-on-r lUO through wire 4, terminal XIV, wire 4,'tere m'nal VI, next Wire 4, lamp L. The lighting of this 4lamp is thus an indication that theshutter has been opened and the selenium cell exposed.

By the contact established between the spring z1 and the terminal XVI Icircuit is extended to the next detector box.

-When the contact arm fu leaves the spring n this spring bends back against the spring n1 and thus establishes a connection with the magnet coil o and prepares a circuit for the closing of the shutter by the coil o and armature z.

' At the same time a current iows from the positive pole of the battery Bz through the wire 8, terminal I, next Wire 8 to the terminal XVII and thence through the selenium cell to the terminal XVIII and through wire 9, terminal III, next wire 9', moving coil w ot the relay R through the wire 9, spring f4, contact closer c2, contact strip b, wire 29, terminal II, back to the negative pole of the battery B2.

When the switch A is turned into its fourth position a circuit is prepared which may be traced from the battery B1 through the wire 1 to the terminal IX, thence.

through lthe next Wire 1 to the contact strip a, the contact closer'c1, to the spring f2 At the spring f1 the clrcuit divides, one part passing through the wire 16, the safety fuse S next wire 16. to the contacts k1, k2 of the relay R, and the other part extending thrqugh the wire 6 to the contact arm m. From the negative pole of the battery B1 the prepared circuit, which is 'as yet unclosed, mgy be traced through the wire 3, terminal next wire 3 through the bell G, lamp L through 12 and 13 respectively to the contacts e1 and e2. A branch of the prepared circuit extends from the negative pole of B1 and the terminal X by wire 33 through the door lock T and by Wire 23 the supply-main switch E and back through the terminal VII, wire 14, 12 to the contact e1.- The supervisory current from the battery B2 tothe selenium cell flows as described in connection with the second position of the switch A. The system is now prepared 'to give an alarm.

. Before the alarm system is switched on,

the protectedroom in.` which the burglar or lire detector containing the selenium cell is causin installed is referably made dark by letting down the binds or in any other suitable way. If a burglar now switches on an electric Vcket lamp or lights 'a match, or if a spar proceeds from an incipient fire, the sensitive selenium cell J `will be illumined a change of its electrical resistance. This c ange of resistance affects the highly sensitive moving coil relay R causing its movable contact or ointer Z to move up against the adjustab o contact' k1, andthus Lacasse hand terminals of the relay R. The circuit thus affected may be traced as follows: from the positive pole of the battery B1 through the wire 1 to terminal IX, next wire 1, contact strip a, and thence through the contact closer c1 to spring f3. At this lspring the current divides, one part iowing through the wire 16, safety fuse S, wire 16, adjustable contact lo, movable contact Z, wire 26, magnet coil a9, Wire 3, terminal X, next Wire 3, to the negative pole of the battery B1; and the other part of the said current flowing from the spring f3 through the wire 6', lcontact'arm m, springs e1, e2. At the springs e1, e2 another Adivision of the current takes place, one part flowing through wire 13 to the lamp L, a second part passing through the wire 12 to the bell G3, and a third part` ,flowing through'the wire 14 to the door-lock again in the wires 3 and the terminal X and return to the battery B1, By employing the contacts e1, e2 of the electromagnetic switch to close the circuits including the lamp L,

bell G, lock T and automatic switch E, the delicate contacts of the moving coil are relieved of the necessity of carrying these relatively strong currents..

A high resistance W which is connected in parallel to the coil fw of the relay R by wires 15, 16 is provided for the purpose ofeffecting the correct balance between the responsiveness of the relay R and the changeableness 'of the resistance of the selenium cell in cases where the rooms in which the selenium cell is placed cannot be made quite dark. Y A special supervisory device D, which is equipped with a lamp L and a press button d, serves as a tell-tale for secretly checking the attendant of the alarm system from any distant spot. If the system is properly switched on the followin circuit will be closed on pressing the pus button d; positive pole of the battery B1, wire 1 terminal IX, next wire 1, contact strip a, contact closer c1, spring f1, wire 11, terminal VIII, next wire-11, push button d, lamp L, wire 23, terminal next wire 3, negative pole of the battery B1. kThe lamp L will thus be lighted andv indicate that the attendant has done his duty.

The selenium cell J may be arranged in an suitable manner in a box or unconspicuously installed behind a transparent mirror. v

' I claim:

1. An electric alarm system comprising an alarm signal, controlling relays, a light detecting device, a cover member, e octroresponsve means for operating said :nem-

A ber to cover the said. light detecting device, v' means for removing. the cover member fromI the light detecting device, means for actu ating the alarm signal with the aid of the controlling rela s when light beams impinge upon the light etecting device, and a switch and associated circuits for selectively controlling said means and said alarm si nal.

2. An alarm system comprising an a arm circuit, a controlling circuit including a' controlling relay for closing the alarm circuit, a selenium cell and a battery, a casing containing the selenium cell, a shutter on the said casing for exposing and covering the said selenium cell, a multiple-blade switch having contacts for opening and closing said alarm and controlling circuits and contacts and associated circuits for checkin the correct exposure and covering the sai cell.

3. An alarm system comprising an alarm signal, a controlling relay, a selenium cell and a circuit from said selenium cell to said p relay, a casing containing the selenium cell,

ashutter on the said casing with a cellobscuring and a cell-exposing position, a

. primary checking circuit closed by the shutter when in itsv cell-obscuring position, a secondary checking circuit closed' by ,the shutter in its cell-exposing position, a sig* naling means and a switch selectingbetween said primary, said secondary and said selenium cell circuits and connecting said primary and' secondary circuit to said signaL i ling means and said selenium cell circuit to said relay.

4. vIn lan alarm system, an attendants n switch, a casing distant from said switch,

a selenium cell in the said casing, a shutter with a cell-obscuring and a cell-exposing position on the said casing, a plurality of circuit closing means cooperating with said shutter, signalling means at the attendants `station including circuits leading to said closing means for checking the-positions of the said shutter, an alarm circuit/,closing relay operated from said seleniumc'lelhsaid attendants switch selectively controlling said checking and said alarm circuits.

5. In an alarm system, a casing, a shutsaidA selecting means' and 'said' checkingmeans, l

6. An alarm system comp isingv a casing, a selenium cell in thesaidcasing, a. shutter with cell-obscuring and cell-exposing posi tions on the said casing, a plurality of cir' cuit closing means cooperating with said shutter, a checking lamp, primary checking circuits including one of said closing means for checking the cell-obscuring position of the said shutter and including the said lamp,

a relay with .an actuating coil and a movable and an adjustable contact, adjusting circuits including the said actuating coil, the selenium cell, the movable and the adjustable contacts and the said lamp, secondary checking circuits including another of said closing means for checking the cell-exposing position of the said shutter, a bell, -alarml circuits including the bell, the selenium cell and the said relay, and a switch for closing the said primary checking circuits, ad-

justing circuits, secondary checking circuits v andthe alarm circuits in succession.J

In testimony whereof I have signed this specilication in the presence of two witnesses. n

GEORG SCHMIDT.

Witnesses:

MAX JABLowsKI, GERTRUD `Knncziioweuxl. 

